"Elevation Training"? From bio-physiological point of view, unfortunately, complete nonsense. Correct would be "Resistance Training"!

What can not this mask:
this mask has no effect in terms of altitude training! To simulate a real high-altitude training, in turn rises by the concentration of red blood cells and thus the oxygen carrying capacity of blood, you need oxygen deficiency. Lack of oxygen can be found for example at a higher altitude, so take place in some performance sports, for example in cross-country skiers, mountain training camp in height. And the increase in red blood cells is the main goal of a high-altitude training.
Breathing through masks as the advertised here, causing an increased airway resistance (= resistance), but have no effect on the concentration of oxygen and therefore not in the red blood cells. Instead, such masks have only the effect, as if incidentally also Respirators respiratory toxins, the body's own exhaust, ie carbon dioxide, is back again breathed into the lungs increases. In effect, this increases the carbon dioxide concentration in the blood, however, the oxygen concentration remains the same. The vertigo described by some users of these masks and the lack of concentration that can be felt during a workout with this mask, are the first symptoms of self-poisoning with carbon dioxide! If the airway resistance even higher, you could theoretically even fall into a coma Hypercapnic, so in a carbon dioxide-induced unconsciousness.

What this mask on the other hand actually can:
by increased airway resistance increased work of breathing muscles is necessary. These muscles are so trained by training with the mask. In addition, they can actually increase lung capacity, which means that the amount of air in the lungs at maximum inspiration, because at maximum exhalation against the increased resistance of the mask and the last small alveoli will be opened. But this is no high-altitude training.
If altitude training would be so easy to do with such a mask, we would see train marathon runners with gas masks since a few decades. The there is no eye protection, so it would not look much different than with this training mask. Instead, they travel to Gebirgsplateus or use special Hypoxiekammern, ie spaces with reduced oxygen concentration.

Therefore, there are only two points from me because the main result of a high-altitude training, the increase in red blood cells, this mask can not provide course.